The invention concerns an agricultural implement for attachment to a tractor or similar self-propelled vehicle, in particular a mowing machine for the mowing of grass, cereal or other grain crops.
In the course of rationalization of the harvesting operation, agricultural implements with large operating widths are applied in conjunction with correspondingly high powered tractors. This applies particularly to mowing machines, for the mowing of grass and other grain crops, such as, in particular, corn, that are applied as front attachment implements for a tractor equipped with a chopper. The rotating tools here consist of intake and mowing drums, with which the crop is mowed and subsequently conducted to the chopper. In this case the operating gearbox of the tractor that drives the drive arrangement for the intake and mowing drums is formed by the central gearbox or the mowing height gear box of the chopper. Such forage harvesters employ high-powered motors up to 500 PS (metric horsepower) where correspondingly high drive power must be applied to the intake and mowing drums that are employed as rotating tools, of which several may be arranged on both sides of the vertical longitudinal center plane of the machine. Since the intake and mowing arrangements operating as rotating tools form large masses that must be accelerated for the initial acceleration of the mower, the drive arrangement of the tools is equipped with at least one slipping clutch as initial acceleration clutch and simultaneously as a safety clutch by means of which the torque transmitted between the drive shaft on the part of the vehicle and the drive arrangement of the rotating tools is limited in a manner known in itself.
In practical application in operation of such large agricultural implements, it has been shown that the maximum torque that can be transmitted by the slipping clutch during initial acceleration of the machine is frequently exceeded, if the initial acceleration on the part of the tractor is performed with a wide open throttle, contrary to the operating instructions of the manufacturer of the machine, instead of gradually increasing the application of the accelerator or gas pedal. The slipping clutch then slips under certain circumstances for several seconds before a friction locking is established through the spring-loaded, ring-shaped friction disks. During the slippage periods, large amounts of heat is generated in the slipping clutches, which are usually configured as dry clutches, that lead to overheating of the friction surfaces, in particular if the initial acceleration, if necessary, must be repeated several times. The forces that can be transmitted by the clutch components are thereby continuously reduced so that the clutch can become inoperative after only a relatively short operating time.
According to the present invention, there is provided an improved drive for a large mowing machine of the type described above.
An object of the invention is to provide a drive having improved initial acceleration characteristics which are applicable for use in harvesting operations in machines of the type indicated above.
A more specific object of the invention is to provide a drive embodying a slip clutch having a first section in the form of a hub configured as a ring-shaped container filled with fluid, with ring-shaped friction disks being engaged with end plates forming part of the container and mounted on a second clutch section for rotation with the second section which defines a housing surrounding the container, the fluid acting to absorb heat so that over-heating of the friction disks due to improper performance of the starting or initial acceleration process of the implement is largely avoided. The cooling fluid, such as water, contained in the ring-shaped container not only absorbs the heat generated by the clutching process, but conducts it to the surroundings over heat exchange surfaces provided by the ring-shaped container. In this way a considerable increase in the durability of the slip clutch is attained.